Plastic rods for cotton ear swabs and swabs for medical use are primarily extruded continuously and are then cut to specific lengths. They are rarely produced as injection-molded parts. Injection-molded rods are solid (FIGS. 1a and 1b) and consequently weigh a lot.
German Patent 196 42 431 A 1 describes an inter-dental cleaner for a similar use, comprising a rod-shaped, elongated carrier of a first material, which is covered in some surface areas by at least one insert or overlay of a second material that is softer than the first material. The carrier cross section described therein is essentially an optional, in particular oval, round, triangular or flattened shape. The cross section for the selected insert or overlay is also essentially optional, wherein especially oval, round, flattened or triangular shapes are used. However, this method requires the use of several materials. Also, the weight is relatively high because of the high material use.
German Patent 37 09 497 A 1 relates to a mouth swab rod stabilized with a support rod. Owing to the high material use, a swab rod of this type becomes relatively heavy and expensive to produce. Furthermore, a loosely inserted support rod results in an increased danger of injury in case of a rod break.
German Patent 17 41 279 U describes a rod for cotton swabs. The rod is produced from twisted-together cotton and is coated with an adhesive-type coating for the purpose of increasing the rigidity. The rod rigidity is further increased through an inserted layer of Perlon(copyright) wire or other suitable plastic. To be sure, this method leads to an increase in the rigidity, but results in the disadvantage of a high material use and thus leads to a weight increase.
Continuously extruded rods are hollow (FIGS. 2a and 2) and are therefore relatively lightweight.
Continuously extruded cotton ear swab rods, which the invention relates to, have standard lengths of 70 to 73 mm and an outside diameter of 1.5 to 2.8 mm. The inside diameter changes with increasing or decreasing rod weight.
Cotton ear swab rods and the rods of swabs for medical use primarily differ as to the rod dimensions and the fact that swabs for medical use usually have cotton wound around only one end of the rod (FIG. 3). Standard dimensions for the swab rods for medical use are approximately 1.5 mm to 6.0 mm, wherein the rod length ranges from approximately 100 mm to 400 mm. One exemplary embodiment for a standard swab rod for medical use is 140 mm long and has an outside diameter of 4.0 mm.
For a non-problematic further processing, both types of rods require a certain amount of flexural strength, so that they do not bend overly much and jump out of the guide for the winding machine.
The standard rod weights used nowadays are necessary to achieve sufficient rigidity for a further processing and to have sufficient material for the xe2x80x9csealing-in.xe2x80x9d
Sealing-in means that the rod ends have jagged, melted-on areas on the ends, so that subsequently the cotton can stick to the still soft plastic and can then be wound into a specific shape (FIG. 3).
Owing to a notching effect or xe2x80x9ca sealing togetherxe2x80x9d, this sealing-in operation can weaken the hollow rod to a degree that it can break off during the winding of the cotton head already or later on during the use, maybe even in the ear. (See FIG. 4)
In particular, these dangers exist with thin-walled cotton ear swab rods. In the past, experiments were conducted to reduce the rod weight by reducing the wall thickness and to prevent the xe2x80x9csealing throughxe2x80x9d with the aid of grooves on the inside and the outside of the rod (FIGS. 5a and 5b respectively). However, these profiles did not lead to an increase in the flexural strength. A further reduction in the rod weight to below the weights presently standard in the marketplace, given the same workability for cotton ear swabs, was therefore made impossible.
Similar problems as for the cotton ear swabs were encountered for the further processing of swabs for medical use. However, the danger of a sealing through (FIG. 4) is not as high as for the cotton ear swab rods because of the higher wall thickness that is standard for the rods of swabs for medical use.
The above problems generally are achieved according to the present invention by a cotton ear swab device or a swab device used for medical purposes, comprising a rod having a swab on at least one end thereof, with the rod being a continuously hollow extrusion including an outer shell provided with a continuous internal web. Preferably, the internal web is connected once or several times to an internal surface of the shell, either continuously or in sections, with the webs being made of the same material as the shell. Still more preferably, the internal web is connected to the internal surface of the shell at least at three points distributed about the circumference of the internal surface.